Row 1: Ch 33 (last 3 ch count as dc), (dc, ch 1, 3 dc) in sixth ch from hook, skip next 2 ch, dc in next ch, * skip next 2 ch, (dc, ch 1, 3 dc) in next ch–shell made, skip next 2 ch, dc in next ch; repeat from * across, turn.
Row 2: Ch 3 (counts as dc), * (dc, ch 1, 3 dc) in next ch-1 sp, dc in single dc between shells; repeat from * across, ending with dc in last dc, turn.
Rows 3-12 or until piece is square, or almost square: Repeat row 2.
At end of last row, fasten off.
To make this stitch pattern any size, begin with ch multiple of 6 plus 3.